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How to repair crack in subframe? Pictures included

Folks

I found a crack on the crossmember subframe where the torsion bar retaining cap rest. Obviously, it will need to be welded, but how? Does the subframe need to come off or can it be welded in place?

I don't know how this could happen. I'm in the middle of a suspension refresh and found this problem.


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Stephanie
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Old 06-24-2012, 08:46 AM
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You see good used aluminum front crossmembers for sale every now and then for less than $100.
That doesn't look good and I would replace it. All the tig welding time and cost required on that one makes it not worth fixing and it will never be as good as a healthy replacement.
Mechanics I know would toss that one in the trash.
Old 06-24-2012, 09:03 AM
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Sorry for the link to another site, but it's for the used part in question. There's even a quick blurb about one he's selling with a similar issue.

914World.com - A Porsche 914 Community / Forum / Club
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Old 06-24-2012, 09:42 AM
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Quote:
Originally Posted by JFairman View Post
You see good used aluminum front crossmembers for sale every now and then for less than $100.
That doesn't look good and I would replace it. All the tig welding time and cost required on that one makes it not worth fixing and it will never be as good as a healthy replacement.
Mechanics I know would toss that one in the trash.
At $100, it is cheaper to buy one than having it welded. Thanks for the advice. Also, I forgot it was aluminum.

Quote:
Originally Posted by infraredcalvin View Post
Sorry for the link to another site, but it's for the used part in question. There's even a quick blurb about one he's selling with a similar issue.

914World.com - A Porsche 914 Community / Forum / Club
Thanks for the link.
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Old 06-24-2012, 10:02 AM
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I say have it welded by a AWS (American Welding Society) certified welder.
I would remove it and take it to be welded.
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Old 06-24-2012, 10:10 AM
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Originally Posted by pete3799 View Post
I say have it welded by a AWS (American Welding Society) certified welder.
I would remove it and take it to be welded.
Pete, I don't think I can get it welded for less than $100. I just removed the subframe and now I could take it to a shop. Again, I bet the repair cost is $150 to weld. What do you think an estimate would be?
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Old 06-24-2012, 10:40 AM
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You're better off getting a replacement. Welding will change the temper of the aluminum, may or may not be an issue depending on the loading; though it broke where it did for a reason.......
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Old 06-26-2012, 10:12 AM
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Wouldn't be more than 10-15 bucks where I am at. I had those plates heliarced on my bumper for 15. I would get it welded up if it was me.

Last edited by gsmith660; 06-26-2012 at 11:41 AM..
Old 06-26-2012, 11:02 AM
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No real worries about the "temper" changing in the aluminum. You cannot really heat treat aluminum.
Aluminum gains it's particular strength or grade when it is manufactured, it's charateristics can be altered at the mill by either stretching, rolling or other pressure related forms to heighten the strength. Or it can be "solution treated" along with a waiting period of 4 days, this also transforms the raw aluminum into another grade.
The main thing that changes aluminum into various grades, are the addition of trace elements, like silica, magnesium etc.

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Old 06-26-2012, 11:29 AM
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A quick google search
R & R Specialties LLC Metal Fabricators
E-mail them a picture.
I'd quess 50.00 or so.
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Old 06-26-2012, 11:37 AM
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Well, I took both routes. I'm getting the old crossmember welded and bought a replacement. The weld shop will do the repair for $30, which I thought was fair. Now, I bought a replacement, but I'm thinking I may have been taken. After I paid via Paypal, the seller emailed an odd question about the part. A question that a person who doesn't want to ship the part would ask.

Right now, I'm thinking I'll use the welded piece, but if the seller doesn't cheat me then I'll use the replacement. I should know by Friday.

Thanks for all the advice.
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Old 06-26-2012, 01:18 PM
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Quote:
Originally Posted by full quack View Post
No real worries about the "temper" changing in the aluminum. You cannot really heat treat aluminum.
Aluminum gains it's particular strength or grade when it is manufactured, it's charateristics can be altered at the mill by either stretching, rolling or other pressure related forms to heighten the strength. Or it can be "solution treated" along with a waiting period of 4 days, this also transforms the raw aluminum into another grade.
The main thing that changes aluminum into various grades, are the addition of trace elements, like silica, magnesium etc.

Mark
WRONG.

Aluminum can be annealed and soften up. Not many shops temper aluminum.

Note: the metallurgy is not the same as what you are referring to with carbon steel.
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Old 06-26-2012, 04:34 PM
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I agree with unclebilly, the material will anneal, not sure if it had any temper to begin with or if it is just reg cast. If it is a weldable type of aluminum, properly cleaned preheat and welded (GTAW) with a slight added build up in the area it will be quite strong.

That does not look like a high load area on that part, is it possible someone was shoving a pry bar in there or a hook?

If you can find one in good condition it's the better way to go.
Old 06-26-2012, 06:54 PM
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Just wanted to share what the weld looks like. I think the weld shop did a good job. I'm still going to use a newer one I bought, but wanted this one fixed as a backup.


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Old 07-01-2012, 04:37 AM
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Just an FYI, but welding heat treated aluminum will reduce it's strength, unless it's re-heat treated after welding. Something the bicycle frame builders learned quite awhile ago.

HEAT TREATING ALUMINIUM

6061 aluminium alloy - Wikipedia, the free encyclopedia

That said, I'm not sure what alloy Porsche used in the crossmember, but that would be a factor in how strong the repair is.
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Old 07-01-2012, 07:35 AM
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Sorry folks for the errant information, my mind was stuck on the grade of aluminum, and not the treated stage of the aluminum. My apologies.

Mark
Old 07-02-2012, 07:06 AM
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ALL you Guys that know Nothing of welding..Keep chattering...LOL....
It could be welded No problem.
But....There are bigger problems
It was a "strike" or something that broke that..
Replace the part and look for some other damage there
PS -If Al can not be welded we are in a world of hurt LOL Going to go right out and throw my welder away .............OMG LOL
Old 07-02-2012, 01:18 PM
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Quote:
Originally Posted by afterburn 549 View Post
ALL you Guys that know Nothing of welding..Keep chattering...LOL....
It could be welded No problem.
But....There are bigger problems
It was a "strike" or something that broke that..
Replace the part and look for some other damage there
PS -If Al can not be welded we are in a world of hurt LOL Going to go right out and throw my welder away .............OMG LOL
Aluminum can be welded -- but many alloys will not be as strong after welding as before unless the cooling is carefully controlled. Age makes it more brittle, like work hardening, and welding makes it softer in terms of yield strength. Like annealing steel but not Martensite to Pearlite/Ferrite.
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Old 07-02-2012, 05:04 PM
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Yes ,In the Absolute sense ..BUT, In the above example....no prize and no problem...Some of these Geeks on here..I get so tired of B.S.
Maybe they use too much J.B. Weld ? LOL
Old 07-02-2012, 05:08 PM
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Just a side note, this is an access hole. Does it really need to be welded/repaired? From the looks of it, it serves no structural purpose.

The one on my 930 is cracked in the same place and I have no intention of fixing it because I am using coil overs.
Old 07-02-2012, 05:53 PM
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